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Seattle Genetics “Empowered Antibody” Shines at Blood Disease Meeting

The longer Seattle Genetics keeps following cancer patients who took its lead drug candidate, the better the data looks. The Bothell, WA-based biotech company released some stellar (albeit preliminary and without a control group) clinical trial results today that show its “empowered antibody” is able to wipe out aggressive forms of Hodgkin’s disease with minimal side effects.

Seattle Genetics (NASDAQ: SGEN), released the findings today at the American Society of Hematology annual meeting in San Francisco. The company made waves six months ago with an earlier peek of data at the American Society of Clinical Oncology, but now Seattle Genetics has more detailed follow-up to show how patients are doing over time.

The results are truly striking. The trial monitored 44 patients with Hodgkin’s disease and other cancers of the blood that carry a signature protein target called CD-30. The patients were very sick, having relapsed after a median of three prior rounds of chemotherapies, leaving them with no FDA-approved treatment options. They enrolled in the study to get SGN-35, an engineered antibody designed to seek out cancer in the body, avoid healthy tissues, and (here’s the special part) dump an extra lethal dose of chemotherapy inside the tumor cells.

Even under these grim circumstances, researchers found that 17 of the 44 patients (38 percent) had their tumors completely disappear or mostly go away. When they looked at patients who got higher doses that are more likely to be tested in late stages, the data look even better. Of the 28 patients who got those doses, about one-third had their tumors completely disappear, while 93 percent had at least some measureable tumor shrinkage. Those numbers have improved since June, when 23 percent of patients were graded as having complete tumor eradication, and 81 percent of the evaluable patients at the time had some tumor shrinkage.

As time has gone on, the drug’s effect appears to be long-lasting, too. Researchers didn’t report on whether the drug actually helped people live longer—the gold standard of cancer drug development—but they did see that it kept their tumors from spreading for a median time of more than six months. That measurement, called progression-free survival, is a common goal of cancer studies accepted as a “surrogate” the FDA usually accepts as proof that a cancer drug is working.

“We are excited with the exceptional antitumor activity of SGN-35 and have plans to move this agent into pivotal trials in the near future,” said Clay Siegall, CEO of Seattle Genetics, in an e-mail right before he got on a plane to San Francisco to talk with researchers about the results.

Anas Younes, the director of lymphoma/myeloma at MD Anderson Cancer Center in Houston, TX, and the study’s presenting investigator, said in a statement that the data is “encouraging, and provide evidence that SGN-35 may offer an important new therapeutic option for patients in this setting.”